There are two major and four minor studies being conducted: The major studies are (1) A double blind crossover trial of methylphenidate in the treatment of adults with presumptive minimal brain dysfunction; (2) A study of CSF and urinary monoamine metabolites in adults with presumptive minimal brain dysfunction. The minor studies are: (1) Psychophysiological correlates of presumptive minimal brain dysfunction as compared to such measures in normal controls and changes in the psychophysiological measures in response to methylphenidate in both groups; (2) An open (and perhaps a repeated crossover) trial of L-dopa in adults with presumptive minimal brain dysfunction; (3) Studies of urinary, lead, and immuneological activity in MBD children; (4) A determination of the frequency of adult MBD in alcoholic population and a possible trial of pemoline in this group.